Modelling of cyclic fed-batch plus batch polygalacturonase production by Aureobasidium pullulans on raw orange peel
1991
Moresi, M. | Petruccioli, M. | Federici, F.
Cyclic fed-batch plus batch polygalacturonase production by Aureobasidium pullulans in slurry fermentation systems using raw orange peel as substrate was studied in a 3-dm(3) stirred fermentor by setting the main operating variables (T = 297 degrees K; pH0 = 3.2; OP0 = 3% w/v; n = 700 rpm) to optimal values determined previously. In this way, it was possible to stabilize enzyme excretion at 130-140 VU cm-3. The time course of this fermentation process in terms of cell growth, substrate consumption and enzyme synthesis was reconstructed with a mean standard error less than 100%, by applying an unstructured model set up in a batch run and further refined in a series of cyclic fed-batch plus batch operations. In particular, the enzyme formation rate was related to the effect of reducing sugars as inhibitors at higher concentrations and as activators at lower levels by using an exponential equation. Moreover, the consumption rate of reducing sugars was found to be linearly related to the cell growth rate, its specific rate being of pseudo-first order with respect to the reducing sugar concentration.
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